Rancor

A rancor is also a large beast in the Star Wars universe. Looking like a huge dinosaur, but with a rounder head and huge clawed arms. A rancor can be seen in the movie Return of the Jedi being kept by Jabba the Hutt for the execution of undesirables, who were to be dropped into the Rancor's cage through a trap door.
The beast is eventually killed by Luke Skywalker, who is dropped into the rancor's cage, but manages to evade it long enough to maneuver the beast underneath a large metal door, which Luke then releases, slamming it into the Rancor's head. Indeed, in the book of short stories "Tales From Jabba's Palace", it is revealed that the rancor was going to be freed the very next day, broken out by its loving trainer (though admittedly this is only an "extended universe" authority). However, this escape was obviously not to be.